WebSockets · Schema

WebSocket Frame

Schema describing the structure of a WebSocket data frame as defined in RFC 6455 Section 5.2. Each frame consists of header fields and a payload.

Full DuplexNetworkingReal-Time CommunicationRFC 6455Web Technology

Properties

Name	Type	Description
fin	boolean	Indicates whether this is the final fragment in a message. The first fragment may also be the final fragment.
rsv1	boolean	Reserved bit 1. Must be 0 unless an extension defines a meaning for non-zero values (e.g., permessage-deflate uses RSV1).
rsv2	boolean	Reserved bit 2. Must be 0 unless an extension defines a meaning for non-zero values.
rsv3	boolean	Reserved bit 3. Must be 0 unless an extension defines a meaning for non-zero values.
opcode	integer	Defines the interpretation of the payload data. Opcodes 0x0-0x2 are for data frames, 0x8-0xA are for control frames.
opcodeDescription	string	Human-readable description of the opcode value.
masked	boolean	Indicates whether the payload data is masked. All frames sent from client to server must be masked. Frames from server to client must not be masked.
maskingKey	string	A 32-bit value used to mask the payload data. Present only when masked is true. Represented as 4 bytes.
payloadLength	integer	The length of the payload data in bytes. For control frames, this must not exceed 125.
payloadData	string	The application data carried by the frame. For text frames, this is UTF-8 encoded text. For binary frames, this is raw binary data.

View JSON Schema on GitHub

JSON Schema

{
  "$id": "websocket-frame.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "WebSocket Frame",
  "description": "Schema describing the structure of a WebSocket data frame as defined in RFC 6455 Section 5.2. Each frame consists of header fields and a payload.",
  "type": "object",
  "required": [
    "fin",
    "opcode",
    "masked",
    "payloadLength"
  ],
  "properties": {
    "fin": {
      "type": "boolean",
      "description": "Indicates whether this is the final fragment in a message. The first fragment may also be the final fragment."
    },
    "rsv1": {
      "type": "boolean",
      "default": false,
      "description": "Reserved bit 1. Must be 0 unless an extension defines a meaning for non-zero values (e.g., permessage-deflate uses RSV1)."
    },
    "rsv2": {
      "type": "boolean",
      "default": false,
      "description": "Reserved bit 2. Must be 0 unless an extension defines a meaning for non-zero values."
    },
    "rsv3": {
      "type": "boolean",
      "default": false,
      "description": "Reserved bit 3. Must be 0 unless an extension defines a meaning for non-zero values."
    },
    "opcode": {
      "type": "integer",
      "description": "Defines the interpretation of the payload data. Opcodes 0x0-0x2 are for data frames, 0x8-0xA are for control frames.",
      "enum": [0, 1, 2, 8, 9, 10],
      "examples": [1]
    },
    "opcodeDescription": {
      "type": "string",
      "description": "Human-readable description of the opcode value.",
      "enum": [
        "continuation",
        "text",
        "binary",
        "connection close",
        "ping",
        "pong"
      ]
    },
    "masked": {
      "type": "boolean",
      "description": "Indicates whether the payload data is masked. All frames sent from client to server must be masked. Frames from server to client must not be masked."
    },
    "maskingKey": {
      "type": "string",
      "description": "A 32-bit value used to mask the payload data. Present only when masked is true. Represented as 4 bytes.",
      "pattern": "^[0-9a-fA-F]{8}$"
    },
    "payloadLength": {
      "type": "integer",
      "minimum": 0,
      "description": "The length of the payload data in bytes. For control frames, this must not exceed 125."
    },
    "payloadData": {
      "type": "string",
      "description": "The application data carried by the frame. For text frames, this is UTF-8 encoded text. For binary frames, this is raw binary data."
    }
  },
  "additionalProperties": false
}